iPads predict user input https://developer.apple.com/documentation/uikit/touches_pres... . Did they do this back when this article was written or is this a newer thing that lets them get to even lower user perceived latencies than 30ms?

In general, predicting user input to reduce latency is a great idea and we should do more of it, as long as you have a good system for rolling back mispredictions. Branch prediction is such a fundamental thing for CPUs that it's surprising to me that it doesn't exist at every level of computing. The JavaScript REPL's (V8's REPL) "eager evaluation" where it shows you the result of side-effect free expressions before you execute them is the kind of thing I'm thinking about https://developer.chrome.com/blog/new-in-devtools-68/#eagere...